EFFETS DE DIFFERENTS TAUX DE FUMIER SUR LES POPULATIONS DE MAUVAISES HERBES, LA VERSE ET LE RENDEMENT EN GRAINS DES CEREALES

Abstract

The effect of four rates (9–36 t/ha) of sheep manure applied in the fall was compared to conventional inorganic fertilization (49 kg of N, 60 kg of P2O5 and 60 kg of K2O/ha) applied at seeding on three species of cereals. Weed populations, lodging and grain yields were recorded on oats (Avena sativa L.), barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) from 1976 to 1978 on the St-André sandy loam and in 1977 and 1978 on the Kamouraska clay. The manure applied came from sheep fed entirely with hay silage. The various rates of sheep manure had no effect on weed population since no significant difference has been observed between the organic and inorganic fertilization. Lodging did not occur in any of the plots, irrespective of the soil type, during the 3 yr of the experiment. For the two soil types, the grain yields of oats, barley and wheat were usually higher on plots that received 27–36 t/ha of sheep manure than on plots that received inorganic fertilizer. The rates of 9 and 18 t/ha of manure resulted in grain yields significantly lower. An application on all plots of 15 kg/ha of inorganic nitrogen in the spring of 1978 has sensibly increased the grain yield. These results suggest that the fall spreading and the incorporation into the soil of 36 t/ha of sheep manure followed by an application of about 15 kg/ha of inorganic nitrogen in the spring provide a very satisfactory grain yield and do not increase the incidence of lodging and weed infestation.